1. Field of the Invention
This invention relates to method of making a catalyst component. A metallocene compound is supported on a silica material treated with an alumoxane co-catalyst and complexed with the alumoxane. The supported metallocene catalyst may be used in the polymerization of olefins, such as propylene. The temperature of the process for supporting the metallocene on the silica affects catalyst efficiency.
2. Description of the Prior Art
Metallocene catalysts for the polymerization of olefins are known in the art and have been known at least since U.S. Pat. No. 4,542,199, which described use of a catalyst to produce polyethylene. Since that time, patents have issued relating to isospecific and syndiospecific metallocene catalysts. Examples of these patents include U.S. Pat. Nos. 4,794,096 and 4,892,851, respectively, the disclosures of which, together with the disclosure of U.S. Pat. No. 4,542,199, are hereby incorporated by reference.
These patents disclose metallocene catalysts that are basically a complex derived from a cyclopentadiene, i.e., a metal derivative of cyclopentadiene, which has been ionized by an ionizing agent to form an active cationic metallocene catalyst. It has also become known in the art that metallocenes may be supported on an inert non-reactive material.
In U.S. Pat. No. 5,106,804 a zirconocene is supported on magnesium dichloride. The contact between the metallocene, the solid support and an organoaluminum compound at a temperature from 0.degree. C. to the boiling temperature of the hydrocarbon solvent employed in the solutions and is preferably from 0.degree. C. to 110.degree. C. This patent states that in a two step process of contacting the solid support with the organoaluminum and then contacting the solid support with the metallocene, the temperature of the first step may be different than that of latter.
In U.S. Pat. No. 5,126,301 a fine particle carrier was treated with a metallocene and an aluminoxane, either consecutively or simultaneously. The preferred process was to treat the carrier first with the metallocene, then the aluminoxane. The temperature at which treatment with a solution of the metallocene occurred was -50.degree. C. to 110.degree. C, and preferably from 0.degree. C. to 80.degree. C.
In U.S. Pat. No. 5,183,867 a metallocene, an alumoxane and a nonmetallocene containing transition metal compound are reacted on a support at a temperature from 0.degree. C. to 100.degree. C. In the working examples the catalysts were made at 25.degree. C. and 80.degree. C.
In U.S. Pat. No. 5,281,679 an alumoxane is deposited on a hydrated silica gel by a reaction between the water and an aluminum trialkyl. A metallocene is then complexed with the alumoxane is a slurry at ambient temperature or at an elevated temperature of about 75.degree. C.
In U.S. Pat. No. 5,296,565 a particulate carrier, an organoaluminum oxy compound, a metallocene and, optionally, an organoaluminum compound are mixed and contacted to form a supported carrier. The temperature at which the mix/contact takes place is -100 to 200.degree. C., preferably -70 to 100.degree. C. A range of -30 to 200.degree. C. is given for mixing and contacting the carrier and the organoaluminum oxy compound is given but no range is given for mixing the metallocene. In the working examples mixing and contacting the metallocene occurred at 30.degree. C. and room temperature.
In U.S. Pat. No. 5,397,757 a metallocene complex, carbon tetrachloride or carbon tetrabromide, an organomagnesium compound and trimethylaluminum were combined to avoid use of aluminoxane to activate the catalyst. The metallocene was supported on silica by slurrying at 20-60.degree. C., preferably 30-55.degree. C.
In U.S. Pat. No. 5,529,965 a catalyst having a metallocene component and a non-metallocene component on silica containing water and an organometallic compound, such as trimethyl aluminum, was used to polymerize ethylene. In the working examples the catalytic components were supported on the silica at 165.degree. F. (74.degree. C.).